Method of and means for finishing printing plates



Aug. 13, 1929. H. E. WOODWARD METHOD OF AND MEANS FOR FINISHING PRINTINGPLATES Filed Nov. 26, 1926 4 Sheets-Sheet A g- 1929- H. E. WOODWARD1,724,741

METHOD OF AND MEANS FOR FINISHING PRINTING PLATES Filed Nov. 26, 1926 4Sheets-Sheet 2 Q Q F-M T IT k N W e/7760 a 5. Wad/494a QQ mm Aug. 13,1929.

H. E. WOODWARD 1,724,741 METHOD OF AND MEANS FOR FINISHING PRINTINGPLATES Filed Nov. 26, 1926 4 Sheets-Sheet 3 Patented Aug. 13, 1929.

UNITED STATES HAROLD E. WOODWARD, OF UNIVERSITY CITY, MISSOURI.

METHOD OF AND MEANS FOR Application filed November The invention relatesto methods of and means for finishing printing plates, one of theobjects being to very accurately finish the back and face of a printingplate, so as to provide the desired surfaces on each side of the plate,at the same time removing the excess material from the back of the plateto reduce the plate to a predetermined thickness.

A further object is to obtain a very high degree of accuracy in thesefinishing operat-ions in an extremely simple manner, requiring verylittle time, and without the ex ercise of any special skill or labor onthe part of the operator.

Prior to this invention, printing plates and especially electrotypeshave been formed with more or less irregular printing faces, andit hasbeen customary to employ a skilled operator for the purpose of locatingall of the printing faces in the same plane, or in predetermined planesdesired for the printing operation. In following the old practice, theoperator first ascertains the locations of undesirable depressions, orlow spots in the printing .face, and he then subjects the back of theplate to numerous hammering operations at the predetermined areas forthe purpose of flattening the print- 0 ing face. These operationsrequire a great deal of time on the part of a skilled operator, andafter the face has been thus finished to the satisfaction of theoperator, the back of the plate is quite irregular as a result of thehammering. Therefore, the next operation in the old p "actice consistsin finishing the back of the plate, and the workman endeavors to performthis operation without changing the condition of the face of the plate.

The highest accuracy cannot be obtained in this old practice, for theelimination of irregularities in the printing face depends mainly uponthe judgement of a workman using rather uncertain means to locate theinaccuracies and a hammering device to remove them.

Some printing plates have areas requiring a large amount of ink andother areas requiring only a relatively small quantity. For example, alarge background to be printed in a solid color is often associated withsmall letters, or with a half-tone consisting of numerous minute dots,all in the same plate, and in such cases care must be FINISHING PRINTINGPLATES.

26, P326. Serial No. 150,858.

exercised to avoid the delivery of too much ink to the small projectionson the printing plate. supplied with enough ink to properly print thelarge background, but the pressure of the roll on the small projectionsshould be relatively slight, so as to avoid blurring vhic-h occurs whentoo much ink is applied to such projections.

Therefore, a further object is to form depressions in the areas ofhalf-tones or other small projections on the printing plates, and tovary the depth of the depressions in accordance with conditions found inthe plate. For example, a half-tone comprising numerous minuteprojections may be depressed about ten one-thousandths ,of an inch,while letters large enough to be easily read, may be depressed aboutfive one-thousandths when surrounded by a background printed in a solidcolor. I' will hereafter describe a method in which the desireddepressions can be formed during the operation of finishing the back andface of a printing )late.

\Vith the foregoing and other objects in view, the invention comprisesthe novel method, construction, combination and arrangement of partshereinafter more specifically described and illustrated in theaccompanying drawings, wherein is shown the preferred embodiment of theinvention. However, it is to be understood that the inventioncomprehends changes, variations and modifications which come within thescope of the claims hereunto appended.

Briefly stated, the method herein described comprises the operation ofsimultaneously finishing the back and face of a printing plate, and ifdesired this single operation may include the step of depressing an areaof the face of the plate. In the preferred form of the invention, theplate is pressed between a. finishing member contacting with the .faceof the plate and another finishing member cont-acting with the back. Oneof these finishing members may be a rotating cutting member contactingwith the back .of the plate to remove excess material and to provide thedesired flat back surface. The other finishing member has asurfacecorresponding to the desired printing face, and during the cuttingoperation the plate is subjected to a pressure great enough to cause itsface to conform to this surface. The plate is of. course flexible enoughto The yieldable inking roll should be yield in response to the highpressure, so that the printing face will accurately conform to thesurface of the finishing member contacting therewith. 1 ill hereaftershow how an under-lay can be used as a deforming member to producedepressions in the face of the plate.

Fig. 1 is a top view of a machine embodying. the features of thisinvention, a portion of the bed being broken away.

Fig. 2 is a longitudinal section taken approximately on the line 2-2 inFig. 3.

Fig. 3 is an end view of the machine, with some of the parts shown insection.

F at is an exaggerated diagram showing a portion of a cutting rollcontacting with the back of a plate, and an under lay between a bed andthe face of the plate.

Fig. 5 is an enlarged fragmentary detail view showing printing elementson the face of a plate as they appear before the finishing operation.

Fig. 6 shows the same elements they appear after the finishingoperation.

To illustrate one form of the invention, 1. have shown a printing plateA adapted to be finished while confined under pressure between a rotarycutting-roll 1 and a bed 2, the latter having a fiat top surface toreceive either the printing face of the plate, or an under-lay B whichwill be hereafter dcscribed.

The rotary cutting roll 1 is mounted in bearings 3 and provided withdriving gears 4; which may be driven by any suitable power. The bearings23 are adjustable vertically to move the cutting roll toward and awayfrom the bed 2. Any suitable means may be eniploycd to adjust thesebearings and to simplify the illustration I have shown plain screws 5above and below said bearings. The

roll 1 is formed with spiral cutting ribs 3' on its periphery.

Straight ribs, or bars, 7 are located at a angle to each other on thebed 2, and the plate to be'finished is arranged in the corner former atthe junction of these ribs, as shown in Fig. 1. The bed 2 is slidablymounted on horizontal faces 8 at the sides of a base 9, and thisslidable bed has a pair of large ribs 10 at the bottom.

A feed screw 11, arranged longitudinally of the bed, lies betweentheribs 10 and passes through a traveling nut member 12, the latterhaving wings 13 extending into recesses 14- formed in said ribs 10. Thenut 12 travels in response to rotary movements of the screw 11, therebyimparting longitudinal movement to the bed 2. The screw can be rotatedin opposite direct-ions'to reciprocate the bed. A worm. gear 15 on oneend of the screw is driven. by a worm 16 on a shaft 17. The screw 11 issupported in bearings 18.

The nut 12 is closely fitted to the walls of the recesses in the ribs10, so as to transmit longitudinal. movement to the bed 2, but thisinterlocking connection does not revent transverse movements of the bed,and while this bed is moving longitudinally it is preferablyreciprocated transversely, thereby impa'rting a wabbling motion to theprinting plate as it travels under the cutting roll 1.

To illustrate this feature]: have shown elongated gear teeth 19 at thebottom of one of the ribs 10, and segmental gears 20 and 21 adapted tomesh with said teeth. The segmental gears are fixed to a shaft 22mounted in bearings 23, and one of said gears is provided with anoperating arm 24 to which an operating rod 2 1' is connected for thepurpose of oscillating the segmental When the machine is in service, thebed 2 slides on the horizontal faces 8. Itis moved longitudinally bymeans of the screw 11 and nut 12, and at the same time oscillated tansversely by the action of the segmental gears 20 and 21 meshing withthe teeth 19. T iis wabbling motion does not vary the distance betweenthe horizontal top face of the bed and the horizontal cutting roll 1,but it aids in the operation of shaving the back of the plate andenables this operation to be carried out while the bed is movinglongitudi nally in either direction.

The under-lay B, shown in Fig. l, comprises a sheet of metal 25contacting with the horizontal top face of the bed 2, fillers 26 on thetop of said metal sheet, and thin sheet material 27 extending over thefillers and having their margins cemented or otherwise secured to themetal sheet 25. The fillers 26 will vary in thickness in accordance withthe depths of the depressions to be formed in the face of the printingplate, and it is to be understood that this f'e ture has beenexaggerated for the purpose of illustration in Fig. 4. The actual depthof a depression is only a few thousandths of an inch. 7 a

Fig. 5 is an exaggerated view suggesting the condition of the printingface before the'finishing operation. The elements 28 may be regarded asthe tiny members forming the printing face of a half-tone, or as themembers for printing small letters. In either case, if they are formedon a plate which is prepared to also print a large surface in a solidcolor, the small inembers should be depressed so they will not receivean excess of ink from the inking roll. The under-lay B is thereforeprepared with fillers 26 of the desired thickness in the areas to bedepressed.

Fig. 6 suggests the condition of the face of the plate after it has beenpressed onto the top of the under-lay. The printing faces Ill) of thedepressed elements 28 lie in the same plane, and the entire face of theplate ac curately conforms to the surface of the under-lay. Or, if theunder-lay is not used, the face of the plate will conform to the fiatsurface of the bed 2.

The pressure for this finishing operation is obtained by forcing therough printing plate under the cutter 1 which shaves the back of theplate while forcibly pressing its face onto the bed 2, or onto theunder-lay. The cutting ribs 6 are adapted to make alined discontinuouscontacts with the back of the plate, and as the cutter l is rotated, thecontact points progress in the direction of their alinement. In otherwords the pressure at the cutter is exerted in a progressive manner asthe shaving proceeds from one edge of the plate to the opposite edge,and the bed is preferably wabbled to more effectively distribute thepressure throughout the plate.

In actual practice, I have found that this method very effectivelyeliminates irregularities that have heretofore been removed by hand, andthat it produces a highly accurate printing surface free from numerousdefects that in practice are not removed by the hand operations. Theprogressive pressing operation is similar to the operation of pressingclothing, and the like, by moving a hot iron in various directions overthe article, to obtain results that cannot be accomplished by pressurealone. However, in the present method the pressure is greater and it ispreferably distributed by using spiral cut ting ribs on the roll, aswell as by the motion of the bed which carries the plate.

Instead of mutilating the back of the plate by hand operations intendedto remove defects from the face, the present invention simultaneouslyfinishes the back and face, thereby producing a plate of the thicknessdesired for printing. An extremely high degree of accuracy in all ofthese operations can be easily and quickly obtained by an operatorhaving no special skill in this art.

I claim:

1. The method which comprises simultaneously finishing the back and faceof a printing plate by shaving the back of the plate and at the sametime forcibly shifting improperly located printing elements to thedesired printing positions by pressing the face of the plate onto afinishing member and moving said finishing member to distribute thepressure throughout the plate.

2. The method which comprises simultaneously finishing the back and faceof a printing plate by compressing the plate between a finishing membercontacting with the face of the plate and a rotating cutter havingspiral cutting ribs contacting with the back of said plate.

3. The method which comprises finishing the back of a printing plate andat the same time deforming the plate to provide a depression in theprinting face of said plate.

4. The method which comprises simultaneously finishing the back and faceof a printing plate by shaving the back of the plate and at the sametime forming a depression in the printing face by forcibly pressing theface of the plate onto an under-lay.

5. The method of finishing printing plates which comprises arranging anunder-lay between a flat surface and the face of a printing plate,forcing the face of the plate onto the under-lay to form a depression insaid face, and at the same time shaving the back of said plate.

6. The method of simultaneously finishing the back and face of aprinting plate which comprises deforming the plate between a rotatingcutting roll contacting with the back of the plate and an under-laycontacting with the face of said plate, so as to depress the printingelements at the under-lay.

'7. The method which comprises simul taneously finishing the back andface of a printing plate by pressing the plate between a cutting membercontacting with the back and a finishing member contacting with theface, and at the same time imparting a wabbling motion to one of saidmembers without varying the distance between said members.

8. The method of simultaneously finishing the back and face of aprinting plate which comprises arranging an under-lay on a flat bed,shaving the back of the plate, pressing its face onto the underlay toform a depression in said face and at the same time wabbling said bed.

9. In a means for simultaneously deforming and finishing the back andface of a printing plate, a cutting member adapted to contact with theback of the plate, a finishing member having a surface corresponding tothe desired printing face, and means whereby the printing plate ispressed between said members to deform its face to the contour of thefinishing member, so as to shave the back of the plate and at the sametime finish the face.

10. In a means for simultaneously finishing the back and face of aprinting plate, a rotary cutter adapted to contact with the back of theplate, a. bed having a finishing member provided with a surfacecorresponding to the desired printing face, and operating means wherebythe bed is moved to forcibly push the printing plate between the rotarycutter and said surface.

11. In a means for simultaneously finishing the back and face of aprinting plate, a cutting member adapted to contact with the back of theplate, a finishing member having a surface corresponding to the desiredprinting face, and means whereby the printing plate is pressed betweensaid members,

so as to shave the back of the plate and at the same time finish theface, said means including a device whereby a wabbling motion isimparted to one of said members.

12. In a means for simultaneously deforming and finishing the back andface of a printing plate, a rotary cutter having spiral cutting ribsadapted to contact with the back of the plate, a bed having a deformingmember provided with a surface corresponding to the desired printingface, and operating means whereby said bed is moved to press theprinting plate between said rotary cutter and said surface, saidoperating means including a device whereby a wabbling motion is impartedto said bed.

13. In a means for simultaneously finishing the back and face of aprinting plate, a cutting member adapted to make alined discontinuouscutting contacts with the back of the plate, said contacts moving in thedi rection of their alinement, a finishing memher having a surfacecorresponding to the desired printing face, and means cooperating withsaid members to deform and finish both sides of the printing plate.

142. The method which comprises simultaneously finishing the back andface of a printing plate by shaving the back of the plate whilesubjecting the plate to pressure at the shaving element and therebyforcibly pushing the improperly located printing elements to the desiredprinting positions.

15. The method of simultaneously finishing the back and face of asubstantially flat printing plate which comprises confining the platebetween a shaving member contacting with the back of the plate and afinishing member having a flat face contacting with the face of theplate, while pressing the portions of the plate between said shavingmember and the fiat face and thereby forcibly shifting improperlylocated printing elements relative to the other printing elements so asto push said improperly located printing elements onto said fiat face. V

16. The method of simultaneously finishing the back and face of aprinting plate which comprises arranging the plate between a finishingmember contacting with the faceof the plate and a shaving membercontacting with the back of the plate, and compressing the materialbetween said shaving member and finishing member and thereby forciblyshifting the improperly located printing elements relative to the otherprinting elements, so as to forcibly push said improperly locatedprinting elements to the positions desired for printing.

17. The method of simultaneously finishing the back and face of aprinting plate which comprises arranging the printing plate between afinishing member contacting with the face of the plate and a cuttercontacting with the back of the plate, at the same time compressing thematerial between said cutter and finishing member and thereby forciblyshifting improperly located printing elements relative to the'prop erlylocated printing elements, so as to locate each of said printingelements in the desired printing position, and moving both the cutterand the finishing member to perform said forcible shifting operations atall of the improperly located printing elements.

18. The method of simultaneously finishing the back and face of aprinting plate which comprises arranging the printing plate between acutter which shaves the back of the plate and a finishing member havinga fiat face contacting with the face of the plate, at the same timecompressing the material directly between said cutter and the flat faceand thereby forcibly shifting the printing elements which do notinitially contact with said flat face so as to forcibly push theimproperly located printing elements relative to the properly locatedprintingelements, the degree of compression at the cutter being greatenough to force said improperly located printing elements onto said flatface.

In testimony that I claim the foregoing I iereunto affix my signature.

HAROLD E. -W0 ODVVARD.

